Pressure switch



1935- H 1.. VAN VALKENBURG ET AL' 2,020,485

PRESSURE SWITCH Filed April 11, 1954 2 Sheets-Sheet 1 Qua fir ATTORNEY Nov. 12, 1935. H. VAN VALKENBURG El AL 2,020,435

PRESSURE SWITCH Filed April 11, 1934 2 Sheets-Sheet 2 Patented Nov. 12 1935 UNITED STATES PATENT OFFICE PRESSURE SWITCH Application April 11, 1934, Serial No. 719,988

13 Claims.

This invention relates to pressure switches. Objects of this invention are to provide a novel form of pressure switch which will open and close the switch mechanism at predetermined adjustable pressure limits, and which in addition will open the switch and hold the switch in open position whenever the pressure drops below a given minimum.

In greater detail, objects of this invention are to provide a pressure switch which is particularlysuitable for controlling motors operating pumps or other apparatus, such as those used in domestic gas machines where it is necessary to provide for the opening and closing of the motor 5 circuit as the pressure reaches predetermined limits, and to also open the motor circuit if the pressure drops below a given minimum, this invention, therefore, providing for these several conditions and in addition providing adjustable means so that the mechanism which opens the switch at the predetermined minimum may be adjusted to thus adapt the switch for any desired conditions.

Further objects are to provide a pressure responsive switch having the characteristics outlined above in which the switch is of a very coms pact construction and is preferably a two-pole switch so that either both lines of a single phase motor or else two lines of a polyphase motor may be opened whenever the switch moves to open position, in which the parts are enclosed in a casing, and in which manually operable reset means are provided for resetting the switch after it' has been opened at the predetermined minimum pressure hereinbefore discussed, and in which this reset means also gives a visual signal to indicate that the switch has been opened and is held opened due to the occurrence of the predetermined minimum pressure.

The reset means includes a plunger or operating member which is projected outwardly from the casing when the switch has been opened due to the occurrence of the predetermined minimum t presssure, the resetting being accomplished by merely operating the plunger irom the outside without opening the casing.

Further objects are to provide a pressure responsive switch in which the switch operates with a quick motion having a snap action for both opening and closing, and'in which the switch is opened by a quick acting mechanism when the predetermined minimum pressure is reached.

An embodiment of the invention is shown in the accompanying drawings, in which:--

Figure 1 is a vertical sectional view through the device, such view corresponding to a section on the line ll of Figure 2.

Figure 2 is a plan view of the device with the cover of the casing removed.

Figure 3 is a sectional view on the line 33 of Figure 2.

Figure 4 is a sectional view on the line.4-4 of Figure 3.

Referring to the drawings, it will be seen that the device comprises a casing whose lower portion is indicated by the reference character I and whose removable upper portion, preferably telescopically fitting the lower portion, is indicated by the reference character 2. 10

The bottom of the casing I is provided with a cut out portion below which is mounted a downwardly dished bottom plate 3 held in place by means of screws 4. A flexible diaphragm 5 is clamped between the bottom plate 3 and the 0215- 15 ing i, as shown in Figure 1, and thus a diaphragm chamber or pressure cavity is formed, as indicated at 6, below the diaphragm. A pipe fitting 1 opens into the cavity 6 and thus forms the means by which the device may be attached to the pres- 20 sure system and also the means by which the entire device is supported or held in place.

A base plate 8 is mounted within the casing and spaced from the lower portion of the casing by means of a spacer washer or plate 9. A 35 frame member i0 is secured to the base plate 8 and pivotally supports the channel-shaped rock lever l I. This rock lever is provided with a saddle-like portion having an upwardly pressed indented part I2, see Figure 1, within which the 30 upwardly projecting prongs l3 from the diaphragm operated head l4 fit, so that the motion of the diaphragm is transmitted to the rock lever H. The rock lever is loosely pivotally mounted by providing a rearwardly projecting shouldered 35 part l5 which loosely bears against the downwardly turned portion 16 of the frame l0 and which is provided with a rearwardly projecting and upwardly extending arm I l loosely passing through an aperture l8 formed in the wall or 40 plate IS. The purpose of the arm II will appear hereinafter.

'I'hefree end of the channel-shaped lever II is provided with a transverse plate l9 which carries two upwardly projecting prongs 20. These prongs fit within the indented ears 2| of a spring pressed head 22.

This head 22 is downwardly urged by means of the spring 23 whose pressure is regulated by the adjustable nut 24 carried by the threaded stem 50 25, such stem being supported from the frame work in of the casing in any suitable manner.

It is to be noted that the threaded stem 25 projects through the upper or cover portion 2 of the casing and carries a thumb nut 26 which holds 5 the cover 2 removably in plate. A snap acting rock lever or contact actuating lever 21 is pivotally mounted by providing it with knife-edge projecting portions 28 integral therewith and fitting within pear-shaped openings 29 formed in .the 00 walls of the frame work H], as indicated in Figure 1.

This rock lever 21 has one end of a spring 30 attached thereto, the other end of the spring being hooked within the plate IQ of the diaphragm operated lever l l. Thus when the lever i I moves upwardly or downwardly, it will snap the rock lever 21 up or down with a quick snap action. The downward motion of the rock lever 21 may be regulated by means of a set screw 3|, as shown in Figure 1, such set screw being yieldingly held in place by a spring member 32 engaging a flat face of the screw and such screw being accessible from the exterior of the casing.

The switch parts are carried within a Bakelite or other insulating body portion 33 which is secured to the frame member In by means of screws 34 set downwardly within openings 35 and formed in the insulating body portion. Preferably a gasket of fiber or other suitable material, indicated at 33 in Figure 1, is interposed between the member 33 and the frame l0.

As shown in Figures 3 and 4, this insulating body portion is provided with a substantially rectangular cavity 36 within which the movable members 31 of the switches are positioned. These movable members or movable bars are urged downwardly by means of springs 38 seated within sockets 39 formed in the body portion 33. The contact bars 3! are provided with suitable contacts which engage the stationary contacts 40 carried by the contact clips 4|. These contact clips 4| are U-shaped, as shown mostly clearly in Figure 3, and straddle a portion of the body part 33, a terminal screw 42 passing loosely through the upper terminal portion 4! of such contact clips and being threaded into the lower portion of such clips to thereby securely lock these contact members or contact clips in place, and at the same time provide a terminal screw for attaching the conductor. Two contact bars are provided which control two circuits of the polyphase motor or any two lines desired.

A composite member constituting both a guide and a reset member and formed of insulating material is slidably carried within the body portion 33. This composite member is indicated by the reference character 43 and is spring urged upwardly by means of the spring 44, see Figure 1, seated within a recessed or slotted part of the member 43. The member 43 is normally restrained in its lower position, as shown in Figure l, by means of a small detent 45 which is loosely pivotally carried within the upwardly projecting stem 46 of the member 43. This detent has a horizontal portion positioned above the spring 44 so that the spring 44 serves the additional purpose of urging the detent in a counterclockwise direction.

Normally this detent is engaged beneath the stationary lip 41 of a stop and is prevented from excessive inwardmotion by means of a gauge or lower plate 48. The detent 45 is adapted to be disengaged from the catch or stop 41 by means of a small plunger 49 operated by means of the extension arm I! of the rocklever II, as shown in Figure l.

Preferably the exact point of operation of the plunger 49 is adjustable. A simple way is to provide a screw 50 threaded through the upper end of the lever l1 and locked in place by a suitable lock nut Thus when the lover I I rocks downwardly below a predetermined point corresponding to the minimum low pressure hereinbefore mentioned, the plunger 49 will be pressed inwardly by means of the extension or lever l1 and thus will release the trip 45, allowing the combined guide and reset member 43 to move upwardly under the influence of the spring 44.

Attention is now directed to Figures 1, 3 and 4. It will be noted from these figures that the member 43 carries two headed plungers 52 which are respectively positioned beneath the movable con tact bars or members 31 and are adapted to move upwardly to thus open the switch. The lower ends of the plungers 52 are positioned directly above the rock lever 21, see Figure 1, and are struck by such rock lever on upward motion of the lever, thus opening the switches when the pressure exceeds a predetermined value.

When the pressure drops below the normal low value, the switch is closed due to the fact that the rock lever 21 snaps into its lower position, as shown in Figure 1. If, in addition to this, the pressure should drop below the lowest point for which the device is designed, it is obvious that the arm ll of the rock lever ll will, through the medium of the plunger 49, release the detent 45 and allow the combined guide and reset member 43 to move upwardly as hereinbefore described. It is apparent from a consideration of Figures 3 and 4 that this reset and guide member has a portion or upper face 53 which is located beneath the movable contact bars 31 and consequently when the reset member 43 rises, it will open the switch due to the lifting of the contact bars upwardly by engaging the face 53 of the reset member, see particularly Figure 3.

When this minimum pressure has occurred and the switch has been tripped to open position, it is held in open position. However, the stem 46 of the reset member, see Figure 1, projects above the upper portion 2 of the casing and gives a visual indication of this state of affairs. The operator may reset the device manually by merely depressing the stem 46.

The pressure switch, which is independent of the minimum pressure release, forms the subject matter of a co-pending application of Earl F.

Mekelburg Serial Number 678,245 for Pressure switches, filed June 29, 1933.

It will be seen that a very compact and simple type of pressure switch has been provided by this invention which will open and close the electrical switch due to variations in pressure and which additionally will open the switch and hold it in open position upon the occurrence of an excessively low minimum pressure.

It will be seen also that the device may be restored to normal operation by merely depressing 5. the reset plunger or member 46.

While the particular device chosen for illustration is actuated by pressure, it was intended merely as one of several means which respond to fluid condition, and that any fluid condition responsive means could be employed as the actuator.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

We claim:

1. In a device of the class described, fluid condition responsive means, an electric switch, mechanism for operating said electric switch from said fluid condition responsive means for opening and closing said switch in response to two positions of said fluid condition responsive means, and emergency means for opening said switch when said fluid condition responsive means moves to a position beyond one of said two positions, said emergency means holding said switch open irrespective of the subsequent operation of said fluid condition responsive means.

2. In a device of the class described, fluid condition responsive means, quick motion mechanism operated thereby, an electric switch opened and closed by said quick motion mechanism, and emergency means responsive to a further change in the fluid condition beyond that required to operate said switch for holding said switch open, said emergency means holding said switch open irrespective of the subsequent operation of said fluid condition responsive means.

3. In a device of the class described, fluid condition responsive means, quick motion mechanism operated thereby, an electric switch opened and closed by said quick motion mechanism, emergency means responsive to a further change in the fluid condition beyond that required to operate said switch for holding said switch open, and manual reset means'for resetting said last mentioned means after said last mentioned means has operated, said emergency means holding said switch open irrespective of the subsequent operation of said fluid condition responsive means.

4. A pressure responsive switch comprising pressure responsive means, an electric switch opened and closed by said pressure responsive means for normal maximum and minimum pressures, and emergency means for opening said switch when the pressure falls below normal minimum, said emergency means holding said switch open irrespective of the subsequent operation of said pressure responsive means.

5. A pressure responsive switch comprising pressure responsive means, an electric switch opened and closed by said pressure responsive means for normal maximum and minimum pressures and normally adapted for repeated automatic opening and closing movement, and means for opening said switch and holding said switch open when therpressure falls below normal minimum, said means holding said switch open irrespective of subsequent rise in pressure.

6. A pressure responsive switch comprising pressure responsive means, an electric switch opened and closed by said pressure responsive means for normal maximum and minimiun pressures and normally adapted for repeated autoy matic opening and closing movement, a portion of said switch being biased towards open position, means for tripping and releasing the biased portion of said switch when the pressure falls below normal minimum, and manual reset means i or restoring the switch to a position for subsequent closing after said last mentioned means has operated.

7. A pressure responsive switch comprising pressure responsive means, an electric switch operated thereby and normally adapted for repeated automatic opening and closing movement, and low pressure responsive means for rendering said switch temporarily inoperative by subsequent operation of said pressure responsive means upon the occurrence oi a predetermined low pressure.

8. A pressure responsive switch comprising pressure responsive means, an electric switch operated thereby and normally adapted for repeated automatic opening and closing movement, low pressure responsive means for rendering said switch temporarily inoperative by subsequent operation of said pressure responsive means upon the occurrence of a predetermined low pressure, and manual reset means for restoring said switch to normal operation.

9. An automatic switch comprising switch mechanism, fluid condition responsive means for actuating said switch mechanism, intermediate means between said fluid condition responsive means and said switch mechanism for transmitting motion to said switch mechanism from said fluid condition responsive means, a movable guide for said intermediate means adapted to additionally operate said switch to open said switch, and additional means controlled by the condition of said fluid for controlling the motion of said movable guide.

10. An automatic switch comprising switch mechanism, fluid condition responsive means for actuating said switch mechanism, intermediate means between said fluid condition responsive means and said switch mechanism for transmitting motion to said switch mechanism from said fluid condition responsive means, a movable guide biased towards switch open position for said intermediate means adapted to additionally operate said switch to open said switch,'and additional means controlled by the condition of said fluid for controlling the motion of said movable guide.

11. An automatic switch comprising switch mechanism, pressure responsive means for actuating said switch mechanism, intermediate means between said pressure responsive means and said switch mechanism for transmitting motion to said switch mechanism from said pressure responsive means, a movable guide for said intermediate means adapted to directly contact with said switch to open said switch and biased towards switch open position, and low pressure responsive means normally holding said guide against motion and releasable upon the occurrence of a predetermined low pressure.

12. An automatic switch comprising switch mechanism, pressure responsive means for operating said switch to open and close said switch upon the occurrence of a predetermined normal maximum pressure or a predetermined normal 45,

means and said switch mechanism for transmit- 60 ting motion to said switch mechanism from said fluid condition responsive means, said intermediate means including quick motion mechanism, a movable guide biased towards switch open position and carrying a portion of said intermediate means and adapted to additionally operate said switch to open said switch, a latch for holding said guide against switch opening motion, and an extension carried by said quick motion mechanism for tripping said latch when said fluid condition responsive means moves beyond a predetermined point.

HERMON L. VAN VALKENBURG.

JOSEF ZELLER. 

